A differential signal is used for high-speed data transmission between different semiconductor integrated circuits (ICs). FIG. 1 is a circuit diagram illustrating a differential transmission system using a differential signal. The differential transmission system 1 includes a first semiconductor IC (hereinafter, referred to as a “transmission circuit”) 2 and a second semiconductor IC (hereinafter, referred to as a “reception circuit”) 4. The transmission circuit 2 and the reception circuit 4 are connected via differential transmission lines 3. The differential transmission lines 3 include a pair of signal lines 3P and 3N. The transmission circuit 2 includes a differential transmitter 6. The differential transmitter 6 drives the differential transmission lines 3 in response to data to be transmitted. The reception circuit 4 has a differential receiver 8.
In some applications, the transmission circuit 2 and the reception circuit 4 are connected via differential transmission lines 3 of a plurality of channels, and a plurality of differential transmitters 6 are embedded in the transmission circuit 2 and a plurality of differential receivers 8 are embedded in the reception circuit 4.
In the differential transmission system 1 of FIG. 1, the following abnormality and failure may occur. FIGS. 2A to 2D are views illustrating abnormality and failure.
Short circuit between the pair of signal lines 3P and 3N of the differential transmission lines 3 . . . FIG. 2A
One signal line 3P(3N) of the differential transmission lines 3 is open . . . FIG. 2B
One signal line 3P(3N) of the differential transmission lines 3 is power short-circuited (power fault) . . . FIG. 2C
One signal line 3P(3N) of the differential transmission lines 3 is ground short-circuited (ground fault) . . . FIG. 2D
When such abnormality and failure occur, it is impossible to perform accurate transmission, and also, a large amount of current may flow to cause heat generation and have a bad influence on other circuits.